G-CSF is a 20 kDa glycoprotein stabilized by two intrachain disulfide bonds and containing a single O-linked carbohydrate moiety. Mature G-CSF has 174 amino acids. G-CSF is synthesized by bone marrow cells, macrophages and fibroblasts. Its main function is to be a growth and differentiation factor for neutrophilic granulocytes and their precursor cells. It is also known in the art that G-CSF activates mature neutrophils. In addition, it stimulates growth/differentiation of various other haemopoietic progenitor cells (in synergy with additional haemopoietic growth factors) and promotes proliferation and migration of endothelial cells. Clinically, G-CSF is used for the treatment of deficiencies in neutrophilic granulocyte levels (neutropenia caused, e.g. by cancer/chemotherapy, AIDS, or bone marrow transplantation).